Conversion of asphaltene-containing hydrocarbon charge stocks

ABSTRACT

Asphaltene-containing hydrocarbonaceous charge stocks are reacted with hydrogen in contact with a catalyst comprising titanium trichloride. The slurry-type process may be effected with the titanium trichloride being composited with a refractory inorganic oxide carrier material. A preferred mode of operation involves unsupported titanium trichloride being admixed with the fresh charge stock.

United States Patent 91 Gleim 51 Jan. 30, 1973 CONVERSION OF ASPHALTENE- CONTAINING HYDROCARBON CHARGE STOCKS [75] Inventor: William K. T. Gleim, Island Lake,

[73] Assignee: Universal Oil Products Company,

Des Plaines, 111.

22 Filed: Aug.30,1971

211 App1.No.: 176,304

52 U.S.Cl. ..208/l08,208/44,208/213,

252/441 511 Int.Cl. ..Cl0gl3/08,C10g1/06,C10g23/02 5s Fieldof Search ...208 44, to, 108, 213; 252/441 [56] References Cited UNITED STATES PATENTS I 3/1939: Pier et a1. ..208/108 2,191,156 2/1940 Pier et al. ..208/9 2,221,952 11/1940 Pier et al. ..208/9 2,865,841 12/1958 Hoekstra ..208/108 2,773,836 12/1956 Shalit et a1... ..252/437 3,592,761 7/1971 Cole et a1. "208/108 3,668,109 6/1972 Kiovsky et al ..208/10 3,258,418 6/1966 Pitchford et a1 ..208/44 Primary Examiner-Delbert E. Gantz Assistant ExaminerG. E. Schmitkons Attorney-James R. Hoatson, Jr. et a1.

[57] ABSTRACT 6 Claims, No Drawings asphaltenic material.

CONVERSION OF ASPHALTENE-CONTAINING HYDROCARBON CHARGE STOCKS APPLICABILITY OF INVENTION The invention described herein is adaptable to a process for the conversion of asphaltene-containing petroleum crude oils into lower-boiling hydrocarbon products. More specifically, the present invention is directed towards a catalytic process for continuously converting atmospheric tower bottoms products, vacuum tower bottoms products, (vacuum residuum), crude oil residuum, topped crude oils, coal oil, oils extracted from tar sands, etc., all of which are sometimes referred to in the art as black oils, and which contain a significant quantity of asphaltenic material. In particular, the process described herein affords a high degree of asphaltene conversion to hydrocarbon-soluble products, while simultaneously effecting a substan tial conversion of sulfurous and nitrogenous compounds to reduce the sulfur and nitrogen concentration. v

Petroleum crude oils, particularly thehe'avy oils extracted from tar sands and vacuum residuum, contain high molecular weight sulfurous compounds in exceedingly large quantities. In addition, these black oils contain excessive quantities of nitrogenous compounds, high molecular weight organo-metallic complexes comprising principally nickel and vanadium, and This asphaltic material is generally found to be complexed or linked with sulfur and to a certain extent with the organo-metallic contaminants. An abundant supply of such hydrocarbonaceous materials currently exists, most of which have a gravity less than about 20.0API. This material is generally further characterized by a boiling-range in dicating that 10.0 percent by volume, and generally more, has a normal boiling point above a temperature of about 1050 F.

Theprocess of the present invention is particularly directed toward the catalytic conversion of black oils into distillable hydrocarbons. Specific examples of black oils, illustrative of those to which the present invention is especially applicable, are a vacuum tower bottoms product, having a gravity of 7.1A Pl, and containing 4.05 percent by weight of sulfur and 23.7 percent by weight of asphaltenes; and, a vacuum residuum I having a gravity of 8.8API, and containing about 6.0 percent by weight of asphaltic material. The present invention affords the conversion of the greater proportion of such material, heretofore having been thought to be virtually impossible. The principal difficulty resides in the lack of a technique which affords many catalytic composites the necessary degree of sulfur stability, while simultaneously producing lower-boiling products from the hydrocarbon-insoluble asphaltic material. This asphaltic material consists primarily of high-molecular weight non-distillable coke precursors, which are insoluble in light hydrocarbons such as pentane or heptane.

Heretofore, in the field of catalytic processing of asphaltene-containing material, two principal approaches have been advanced: liquid-phase hydrogenation and vapor-phase, or mixed-phase hydrocracking. In the former type of process, liquid-phase oil is passed upwardly, in admixture with hydrogen, into a fixedfluidized catalyst bed. Although perhaps effective in converting at least a portion of the oil-soluble organometallic complexes, this type process is relatively ineffective with respect to the asphaltics. The retention of unconverted asphaltics, suspended in a free liquidphase oil for an extended period of time, results in polymerization and agglomeration. Some processes have been described which rely primarily upon cracking in the presence of hydrogen over a fixed-bed of a particulate solid catalyst. The latter rapidly succumbs todeactivation as a result of the deposition of coke and metallic contaminants thereon. Such a process requires an attendant high capacity regeneration system in order to implement the process on a continuous basis. Briefly, the present invention involves a slurry-type process utilizing titanium trichloride as the catalytic agent, whereby the asphaltic material and catalyst are maintained in a dispersed state within a principally liquid phase rich in hydrogen. The asphaltic material is capable of intimate contact with the catalyst, thereby effecting reaction between hydrogen and asphaltic material; the liquid phase is itself dispersed in a hydrogen-rich gas phase so that the dissolved hydrogen is continuously replenished.

In addition to asphaltenes, sulfurous and nitrogenous compounds, black oils contain greater quantities of metallic contaminants than are generally found in lighter hydrocarbon fractions. A reduction in the concentration of the organo-m'etallic contaminants, such as metal porphyrins, is not easily achieved, and to the extent that the same no longer exert a detrimental effect with respect to further processing. When a hydrocarbon charge stock containing metals is subjected to a catalytic cracking process, for example, to produce low-boiling hydrocarbons, metals become deposited upon the catalyst employed, steadily increasing in quantity until such time as the composition of the catalytic composite is changed to the extent that undesirable results are obtained.

The principal object of the present invention is to provide a more efficient process for the hydrorefining conversion of heavier hydrocarbonaceous material, containing insoluble asphaltenes. The term hydrorefining" as employed herein connotes the catalytic treatment in an atmosphere of hydrogen, of a hydrocarbon fraction or distillate for the purpose of eliminating and/or reducing the concentration of the various contaminating influences previously described, accompanied by hydrogenation and significant conversion into lower-boiling hydrocarbon products. As hereinabove set forth, metals are generally removed from the charge stock by deposition of the same onto the catalyst employed. This increases the amount of catalyst, actively shields the catalytically active surfaces and centers from the material being processed, and thereby generally precludes the efficient utilization of a fixedb,ed system. The preset invention involves the use of a colloidally dispersed catalytic material in a slurry-type process. Although the catalytic agent, titanium trichloride, may be composited with a suitable refractory inorganic oxide carrier material, a preferred technique involves unsupported titanium trichloride. The present process affords greater yields of a liquid hydrocarbon product which is more suitable for further processing without experiencing the difficulties otherwise resulting from the presence of the foregoing contaminating influences.

OBJECTS AND EMBODIMENTS One object of the present invention is to provide a more efficient process for the conversion of asphaltene-containing hydrocarbonaceous charge stocks. A corollary objective is to provide a catalytic slurry-type process utilizing a colloidally dispersed titanium trichloride catalyst.

Therefore, in a broad embodiment, the present invention involves a process for converting an asphaltene-containing hydrocarbonaceous charge stock, which process comprises reacting said charge stock and hydrogen in contact with a catalyst comprising titanium trichloride. In another embodiment, the charge stock is reacted with hydrogen in the presence of about 2.0 percent to about 30.0 percent by weight of hydrogen sulfide.

In a preferred embodiment, the titanium trichloride catalyst is unsupported, and is admixed with said charge stock in an amount from 0.5 percent to about 25.0 percent by weight.

SUMMARY OF INVENTION From the foregoing embodiments, it is readily ascertained that the process of the present invention involves the preparation of a colloidally dispersed catalytic component within the hydrocarbon charge stock from which the contaminating influences are intended to be removed. The colloidally dispersed catalytic component is titanium chloride, which may be employed in and of itself or in combination with a suitable refractory inorganic oxide. Suitable refractory inorganic oxides include alumina, zirconia, silica, magnesia, etc., and' mixtures of two or more. When composited with the refractory carrier material, the titanium trichloride is generally impregnated thereon in an amount within the range of about 1.0 percent to about 30.0 percent by weight. Following impregnation, drying, and calcining, the impregnated carrier material is ground to a finely divided state approximating 100/200 mesh. In a preferred mode of operation, the refractory carrier material is eliminated and the titanium trichloride, in a finely divided state, is commingled directly with the charge stock in an amount in the range of about 0.5 percent to about 25.0 percent by weight. Although increased quantities of titanium trichloride may be employed, they do not appear to significantly enhance the desired results.

Briefly, the process is effected by initially admixing the desired quantity of titanium trichloride with the hydrocarbon charge stock. The resulting colloidal suspension is then passed into a suitable reaction chamber maintained at a temperature within the range of about 225 C. to about 500 C. and under a hydrogen pressure of about 500 to about 5000 psig. It appears that the presence of hydrogen sulfide in the hydrogen atmosphere enhances the catalytic activity of the titanium trichloride, the hydrogen sulfide being present in an amount within the range of about 2.0 percent to about 30.0 percent. The process may be effected as a batchtype operation, or in a continuous manner in either upward flow or downward flow. The normally liquid hydrocarbons are separated from the total reaction zone product effluent by any suitable means, for example, through the utilization of a centrifuge, or settling tanks, the remaining metal-containing sludge being treated as herein after set forth.

The metal-containing sludge is a viscous fluid consisting of the catalytically active metallic component, originally dispersed in the charge stock, some unconverted asphaltic material, soluble hydrocarbons, porphyrinic material containing nickel, vanadium and other metallic contaminants, coke and heavy carbonaceous material, etc. Following the separation of the normally liquid hydrocarbons from the metal-containing sludge, the latter is treated with a suitable organic solvent for the purpose of dissolving residual organic-soluble material such as pentane-soluble hydrocarbon products resulting from the conversion of the insoluble asphaltenic compounds. Any well known organic solvent may be employed for the dissolution of the organic-soluble material in the sludge, and the resulting solution may be subjected to further reaction with hydrogen by recycling the same to combine with fresh hydrocarbon charge'stock. The remainder of the sludge is then treated with a compound having the propensity to regenerate the titanium trichloride. Suitable compounds for this purpose include sulfur monochloride, sulfur dichloride, and their mixtures. The regeneration may be readily effected at a comparatively low temperature within the rage of about 250 C. to about 450 C., the sulfur chlorides being employed in an amount from about 0.1 percent to about 25.0 percent by weight of the material to be treated. The sludge, containing regenerated titanium trichloride, is combined with the fresh hydrocarbon charge stock and reacted with hydrogen as aforesaid. In order to prevent a build up of coke, unconverted asphaltenic material and other carbonaceous residue, a controlled portion of the sludge will bewithdrawn from the process and sent to a suitable metals recovery system.

The following examples are presented to illustrate the process of the present invention and the effectiveness thereof in converting asphaltenic material. It is not intended that the present invention be unduly limited to the method, charge stock and/or operating conditions employed in this illustration.

The charge stock was a vacuum tower bottoms having a gravity of 8.8AP1, containing 6.0 percent by weight of asphaltenic material, 3.0 percent by weight of sulfur, and 4,300 ppm. by weight of nitrogen; the 20.0 percent volumetric distillation temperature was 1055 F. The criteria employed to indicate the degree of conversion, particularly with respect to asphaltenic material, was the Color Index of the product. Obviously, the lighter the color of the product, the lower the Color Index and the greater the degree of conversion. The Color Index was determined by UOP Method 707-71, based upon the information found in Analytical Chemistry, Vol. 34, pp 694-700, 1962.

EXAMPLE I In this, as well as in the following example, the charge stock previously described was employed in an amount of 200 grams. The charge stock and catalytic titanium trichloride were intimately commingled in an 1,800 cc. rotating autoclave with hydrogen at a pressure of atmospheres. Upon heating to a temperature of 400 C., the pressure increased to about 200 atmospheres. These conditions were maintained for a 2- hour period, after which the autoclave was cooled and depressured, and the contents separated to provide a metal-containing sludge and the normally liquid product effluent. The latter was analyzed for Color lndex and gravity.

The first test was made using twenty grams l0.0 percent by weight) of a catalyst consisting of 1.8 percent nickel and 16.0 percent molybdenum composited with a carrier material of 68.0 percent alumina, 10.0 percent silica and 22.0 percent boron phosphate; the catalyst was finely-divided to about 100/200 mesh. This catalyst is described in U.S.'Pat. No. 3,453,219 (Cl. 22 42) 252-432). A significant improvement was observed; the gravity increased from 8.8 to 18.5API and the Color lndexwas lowered from 150.0 to 39.0. The normally liquid product was recovered in an amount of 68.0 percent by weight.

EXAMPLE II Three catalyst charge stock mixtures were prepared, using varying amounts of titanium trichloride and subjected to the reaction conditions previously set forth. The results are presented in the following tabulation:

TABLE: Titanium Trichloride Results The benefits afforded through the use of the titanium trichloride catalyst are readily ascertained from the foregoing tabulated data. The Color Index, indicative of the asphaltene conversion, was significantly improved in all instances, and the gravity increase indicates substantial conversion into lower-boiling products.

I claim as my invention:

1. A process for converting an asphaltene-containing hydrocarbonaceous charge stock which comprises reacting said charge stock and hydrogen in contact with a catalyst comprising titanium trichloride.

2. The process of claim 1 further characterized in that said charge stock is reacted with hydrogen in the presence of about 2.0 percent to 30.0 percent by weight of hydrogen sulfide.

3. The process of claim 1 further characterized in that said titanium trichloride is supported on a refractory inorganic oxide carrier material.

4. The process of claim 1 further characterized in that said titanium trichloride is unsupported.

S. The process of claim 4 further characterized in that said titanium trichloride is admixed with said charge stock in an amount from 0.5 percent to about 25.0 by weight.

6. The process of claim 1 further characterized in that said charge stock and hydrogen are reacted at a temperature in the range of 225 C. to about 500 C. and at a pressure from 500 psig to 5,000 psig. 

1. A process for converting an asphaltene-containing hydrocarbonaceous charge stock which comprises reacting said charge stock and hydrogen in contact with a catalyst comprising titanium trichloride.
 2. The process of claim 1 further characterized in that said charge stock is reacted with hydrogen in the presence of about 2.0 percent to 30.0 percent by weight of hydrogen sulfide.
 3. The process of claim 1 further characterized in that said titanium trichloride is supported on a refractory inorganic oxide carrier material.
 4. The process of claim 1 further characterized in that said titanium trichloride is unsupported.
 5. The process of claim 4 further characterized in that said titanium trichloride is admixed with said charge stock in an amount from 0.5 percent to about 25.0 by weight. 